Traditional diagnostic radiography and cancer therapy use X-ray generators that emit X-rays over a broad energy band which unnecessarily exposes normal tissue during diagnosis and treatment. Monochromatic radiation has been used in specialized settings in attempts to reduce the dose and improve image contrast. However, conventional systems for generating monochromatic radiation may be unsuitable for clinical or commercial use due to prohibitive size, cost and/or complexity. For example, utilizing an inefficient Bragg crystal as a filter or using a solid target x-ray fluorescence to generate monochromatic radiation requires a very large, expensive and powerful broad band synchrotron source, which has not proven practical for clinical settings.
Other conventional techniques include using polycapillary optics to increase the throughput from conventional laboratory X-ray generators, but Bragg crystals are still used to monochromatize. In some therapeutic applications, high energy linear electron accelerators are used to reduce the dose to the skin. However, control over energy specificity is indirect and minimal. It is typically impossible to target a specific type or depth of tissue using a single radiation beam and the radiation is indiscriminant of tissue types, whether malignant or benign. Further, the cost, infrastructure, and personnel requirements of today's treatment facilities is high and it is unlikely to meet even a fraction of society's healthcare needs. Brachytherapy using monochromatic Gamma-ray sources may offer therapeutic benefits as well, but the appropriate choices of radionuclides are limited because Gamma-ray energies and half-lives are fixed by the natural laws of physics.